40 CFR § 35.10040 - Investment-grade ratings.
(a) At the time a project sponsor submits an application, the EPA shall require a preliminary rating opinion letter. This letter is a conditional credit assessment from a NRSRO that provides a preliminary indication of the project's overall creditworthiness and that specifically addresses the potential of the project's senior debt obligations (those obligations having a lien senior to that of the WIFIA credit instrument on the pledged security) to achieve an investment-grade rating and the default risk of the WIFIA loan.
(b) The full funding of a secured (direct) loan or loan guarantee shall be contingent on the assignment of an investment-grade rating by two NRSROs to all project obligations that have a lien senior to that of the Federal credit instrument on the pledged security along with commentary on the default risk of the WIFIA loan.
(c) Neither the preliminary rating opinion letter nor the formal credit ratings should reflect the effect of bond insurance, unless that insurance provides credit enhancement that secures the WIFIA obligation.